1. Field of Invention
The invention relates to crane or jib arms used for live action motion picture or television production, specifically to a method of automatically compensating for camera backpan.
2. Description of Prior Art
When a camera is mounted at the end of a crane or jib arm and swung through space without the operator making any correction, the lens pans through space as shown in FIG. 1a. If it is desired that the camera remain pointed at a fixed compass position in space as the arm is panned in an arc, as shown in FIG. 1B, the camera operator must make a compensating reverse pan of the camera perfectly matched to the speed and direction of the arm. This process is known as backpan. Generally, only operators skilled and practiced at this maneuver can accomplish it perfectly and they require several rehearsals with the operator of the arm to synchronize their respective movements. Any error by the camera operator results in the camera panning away from the desired composition often followed by an overcompensating pan as the camera operator attempts to correct. This movement is called fishtailing. Both faulty composition and fishtailing result in additional retakes at significant cost to the production company.
Before the introduction of remote camera heads, when a camera was mounted on a crane or jib arm, the operator rode with it. Consequently, as the arm began to swing, the operator sensed its movement immediately and made a rapid correction to compensate for the arm's swing.
With the introduction of remote control camera heads for motion picture and television production, the operator was stationed at a distance from the crane and thus lost the ability to feel its movement. Since the operator was no longer riding the crane, the operator's first knowledge of any change in speed or direction came from seeing the composition slip away on the monitor screen, too late to make a timely correction.